Photoshop separations for screen printing shirts: help?

[decay]

I did a painting that I'd like to photograph and run color seps for CMYK printing (or spot color) for t-shirts, most likely on black cotton.

I've started searching YouTube and Google on the process. I'm sure I can handle it.

Do I need to know what kind of inks the printer will be using?

Can I download actions for free that do this conversion? It looks like some tutorials on YouTube rely on these.

https://www.youtube.com/watch?v=0N7V2T7M5h0
(silent, somewhat blurry)

The painting is acrylic, and is more of a comic style, i.e. solid patches of color with some red/orange gradient.



Thanks for any tips. I know some of you here have experience in this.